This invention relates to an improved deflector device of the kind to be installed between a towing vessel and a tow located in water, for example, a streamer, a cable with seismic sources or a seismic source array. The purpose of the deflector is to pull the tow out to the side of the vessel, to position the towed seismic equipment at the desired lateral offset from the vessel.
One such device is described in U.S. Pat. No. 5,357,892. It comprises a wing-shaped deflector body which is positioned generally vertically in the water so as to be completely submerged in use. The deflector is suspended under a float and the tow, which follows the deflector, is suspended at the rear of the deflector wing. The deflector is connected to the towing vessel by means of a tow-line fixed to a point near the front of the deflector wing. The deflector wing is of aerofoil-like cross-section. As it is pulled through the water, a sideways force, or "lift", is exerted on the aerofoil-like wing, while the line to the float provides rolling stability.
The deflectors in current use are very large, typically, 7.5 m high by 2.5 m wide and weigh several tonnes. They are usually suspended around 28 m below the float by means of a fibre rope, and are also provided with a safety chain intended to prevent separation, of the float and deflector wing in the event that the rope breaks.
In bad weather, the upper part of the deflector wing may rise up out of the water, allowing the rope connecting the deflector wing and the float to go slack. If the deflector wing then drops abruptly, the rope, and, possibly, the safety chain, may break or the attachment points may be damaged. it is an object of the present invention to alleviate this problem.